ground perilla seeds
Roasted and ground seeds of the perilla plant, a coarse grey-brown powder with a nutty, faintly earthy and herbal flavour.
Ground perilla seeds come from the same plant as Korean perilla leaves and are roasted before grinding. They taste nutty like sesame, but earthier and with a faint herbal undertone. Because they are rich in oil and starch, they thicken soups and stews and make them creamy and slightly cloudy, which is what they are mostly used for. They are sold hulled as a finer, paler powder and unhulled as a darker, grittier meal with noticeable bits of husk. You can find them in Asian grocery shops with a Korean range or by mail order. The delicate oil turns rancid quickly, so keep the powder tightly sealed in the fridge or freezer.
Substitute:
Freshly toasted ground sesame comes closest and gives the nutty note, but not the earthy, herbal tone, and it thickens soups less, so they stay thinner and less creamy.